Hydraulic pulse generator

ABSTRACT

The pulse generator according to the invention comprises a piston pump with a suction space and a compression space, the piston comprising two movable portions, with limited movability relative one another and of concentric relationship, forming between themselves an overflow passageway from the suction space to the compression space, and coacting surfaces in both portions controlling the overflow through said passageway.

United States Patent Inventor Holger Grallman Villa Solimar, Benicasimde Castellon,

Spain Appl. No. 32,138 Filed Apr. 27, 1970 Patented Dec. 21, 1971Priority Dec. 12, 1969 Sweden 17217/69 HYDRAULIC PULSE GENERATOR 3Claims, 1 Drawing Fig.

U.S. Cl 417/487,

417/5 13 Int. Cl F04b 7/00 Field of Search 417/513,

[5 6] References Cited UNlTED STATES PATENTS 1,039,757 10/1912 Kitton417/513 2,067,997 1/1937 White 417/282 X 481,850 8/1892 Dillenburgm.417/513 1,528,733 3/1925 Dennedy 417/513 3,023,710 3/1962 Tyree 417/513X 7 Primary ExaminerCarlton R. Croyle Assistant Examiner-Richard EsGluckAttorney-Stevens, Davis, Miller & Mosher ABSTRACT: The pulse generatoraccording to the invention comprises a piston pump with a suction spaceand a compression space, the piston comprising two movable portions,with limited movability relative one another and of concentricrelationship, forming between themselves an overflow passageway from thesuction space to the compression space, and coacting surfaces in bothportions controlling the overflow through said passageway.

HYDRAULIC PULSE GENERATOR For a certain type of atomizingcarburetor thefuel has to be supplied with a pulsating pressure to an atomizingnozzle. The pressure surges thereby transferred via the fuel to aresilient valve body in the opening of the atomizing nozzle produce inthe valve body variations, which are prerequisite for correctatomization during carburetor operation. A carburetor of this type isdescribed in greater detail in Swedish Pat. Nos. 224,579 and 305,980.

The fuel supply to such an atomizing carburetor is effected by a pulsegenerator, which in principle operates as a piston or diaphragm pump.For every pressure stroke this pump sends an amount of fuel to theatomizing nozzle of the carburetor. Tests have shown that the pressuresurge produced in the pipe and/or passageways between pulse generatorand carburetor must be hard and distinct. The pressure surges then actlike a hammer blow on the resilient valve body in the atomizing nozzleopening. Practical tests further have shown that it was not possible bypulse generators of conventional construction to effect sufficientlyhard and distinct pressure surges, and that as a result thereof theatomizing carburetor did not operate in an entirely safe and stablemanner at varying operation conditions. This problem had been observedwhen the pulse generator was mounted in a vehicle where the correctoperation of the pulse generator was disturbed by vibrations. Operationalso is negatively affected by an inclined mounting of the pulsegenerator.

The present invention; which has as its object to'eliminate suchdisadvantages, relates to a hydraulic pulse generator comprising a blockwith cylinder bore and, operating therein, a piston on one side of whichis formed a compression space between the piston head and cylinder head,and on the other side of which is formed a suction space. A piston rodand push mechanism impart a short reciprocating motion to the piston soas to compress the liquid medium in a compression stroke and during areturn stroke, fill the compression space with such liquid.

An embodiment of the invention follows with reference to theaccompanying drawing whose sole figure is a longitudinal sectional viewthrough a pulse generator according to the invention.

The pulse generator comprises a pump housing 1, the interior of which isa cylindrical hollow space 2. The upper part of said housing defines acylinder head wherein there is provided a stop valve 3 with associatedspring 4 and an aperture 5 for connection to a pipe leading to thenot-shown atomizing carburetor. Within the space 2, a piston 6 isreciprocably mounted. Said piston comprises two portions, one outerannular portion 7 and one substantially cylindrical inner portion 8. Atthe upper edge, said outer and inner piston portions are so fitted onewithin the other that upon downward motion of the inner portion acone-shaped gap 9 is formed between said two piston portions. A shoulder10 on the inner piston portion and a shoulder 11 on the outer pistonportion define the width of said cone-shaped gap when the piston ismoving downwards. The outer piston portion includes a number ofpassageways 12, through which said gap, and thereby the compressionspace 13, communicate with the suction space 14. For centering the innerpiston portion, a guide 15 rising upwardly from the bottom of thehousing is provided. The piston portion 8 is secured by a screw means 16to a piston rod 17 running in a hollow space 18 in said guide 15. In theupper portion of guide 15 and on the piston rod 17, respectively,shoulders 19, 20 are provided, between which a helical spring 21 ismounted for effecting the return stroke of the piston. The compressionstroke of the piston is effected by a not-shown cam or eccentric actingupon a pressure shoe 22 and via said shoe and the rod 23 which includesabutment 24, acts upon the washer springs 25 which act upon the bushing26 which acts upon the endpiece 27 of the piston rod 17. This powertransmission renders the length of the piston stroke variable and afunction of the pressure produced in the compression space 13. Thispressure, on the other hand, can be adjusted by lessening or increasingthe compression of the washer springs 25.

The pump housing of the pulse generator includes two openings, whereofone, the inlet 28, opens tangentially and the other, the return outlet29, opens radially into the suction space of the pump housing. A pipeconnection 30 in the outlet opening extends a distance into said suctionspace 14.

The pulse generator operates as follows.

' The piston just having arrived at its uppermost position, the gap 9 isclosed entirely and the piston is located at sucha height in thecylinder that the upper edge of the piston contacts the cylinder roof.Thereby the compression space 13 practically is zero. At the beginningof the return stroke of the piston, at the beginning only the innerpiston portion 8 is moving while the outer piston portion 7 is retainedin its uppermost position, due to the friction between portion 7 and thehousing wall. The gap 9 is thereby opened and the liquid in the suctionspace 14 is free to flow upwardly into the compression space 13 via thepassageways l2 and the gap 9. When the shoulder 10 on the inner pistonportion abuts the shoulder 11 on the outer piston portion, gap 9 ismaximum and said outer portion is caused to follow the inner portion tothe lowermost position of the piston while simultaneously thecompression space entirely becomes filled with liquid from the suctionspace. During the subsequent compression stroke of the piston, again atat the beginning only, the inner portion is moving upwardly until gap 9has been closed entirely. During this phase no appreciable pressureincrease takes place in the compression space because said space via thegap 9 communicates with the suction space 14. As soon as the gap 9 isclosed, the outer piston portion is caused to participate in thecontinued motion upwardly, and the liquid in the compression space 13 isforced past the stop valve 3 to the outlet opening 5 from which theliquid via a pipe can be led to the atomizing nozzle of the carburetoror another similar device.

The liquid is supplied to the suction space 14 of the pulse generator bya separate pump, which all the time supplies a quantity of liquidconsiderably exceeding that pumped by the pulse generator to thecarburetor. This liquid excess serves to flush away steam or gasbubbles, which easily fonn in volatile liquids such as gasoline, fromthe suction space of the pulse generator where they otherwisedetrimentally would affect the pump operation. Due to the fact that theinlet to the suction space of the pulse generator is positionedtangentially and the mouth to the return outlet is located as far aspossible inwardly to the center of the suction space, the suction spaceacts as a separator and thereby renders possible an effective separationand removal of gas bubbles found in the suction space. The liquid thusflowing back through 30, 29 can be directed, for example, to thegasoline tank of the car or to some other container or means where gasor vapor bubbles following along can be separated.

The advantages of the pulse generator described above are obvious. Thesimplest shape of the eccentric or cam efi'ecting the piston movement isthe circular shape. This implies that the piston speed becomes a sinefunction, i.e., the piston speed will be at maximum when the drivingeccentric is at an angle of in relation to the longitudinal axis of thepiston. lt is then suitable so to adjust the distance between theshoulder 10 on the inner piston portion and the shoulder 11 on the outerpiston portion that the gap 9 during the upward movement of the pistonis closed at that moment when the piston moves at maximum speed. Herebythe pressure increase in the-compression space will take place extremelyrapidly and be given the nature of that hard and distinct hammer blowwhich, as mentioned before, is of decisive importance for the functionof the means. It was found by practical tests that at a total pistonmovement of 0.70 mm. and if said distance between shoulder 10 andshoulder 11 is 0.35 mm., better results have been achieved with theatomizing carburetor according to the invention than they heretoforehave been achievable with known pulse generators.

What I claim is:

l. A hydraulic pulse generator, comprising: a block having a cylindricalbore therein and a head at one end of said bore, a piston reciprocablyfitted within said bore, a compression cooperating surfaces of saidinner and outer piston portions,

said surfaces being sealingiy seated against each other with said pistonportions being in said first position, and said surfaces being spacedapart to define a liquid passage therebetween with said piston portionsbeing in said second position, said liquid passage communicating saidsuction space with said compression space, a rod means forreciprocatingly driving said inner piston portion, abutment meansrestricting the axial displacement of said piston portions apart fromeach other and thereby defining the maximum spacing apart of saidseating surfaces, said suction space being annular and concentric withsaid inner piston portion, said liquid inlet opening tangentially intosaid annular suction space, and a liquid outlet conduit extendingradially outwardly from the vicinity of the central area of said suctionspace.

2. The pulse generator of claim 1, said cooperating surfaces beingfrustoconical.

3 The pulse generator of claim 1, including a discharge passage in saidhead leading from said comprewion space, a valve closing said dischargepassage, yieldable biasing means urging said valve to a closed position,said valve being arranged to be urged to an open position by pressurewithin said compression space.

1. A hydraulic pulse generator, comprising: a block having a cylindricalbore therein and a head at one end of said bore, a piston reciprocablyfitted within said bore, a compression space being defined between oneside of said piston and said head, a suction space being defined betweenthe other side of said piston and the corresponding other end of saidbore, a liquid inlet leading into said suction space, said pistoncomprising an inner and outer portion, the outer portion being slidinglyfitted against the longitudinal wall of said bore, said inner portionbeing fitted within said outer portion whereby one is axiallydisplaceable to opposed first and second positions relative to theother, a seat defined by respective cooperating surfaces of said innerand outer piston portions, said surfaces being sealingly seated againsteach other with said piston portions being in said first position, andsaid surfaces being spaced apart to define a liquid passage therebetweenwith said piston portions being in said second position, said liquidpassage communicating said suction space with said compression space, arod means for reciprocatingly driving said inner piston portion,abutment means restricting the axial displacement of said pistonportions apart from each other and thereby defining the maximum spacingapart of said seating surfaces, said suction space being annular andconcentric with said inner piston portion, said liquid inlet openingtangentially into said annular suction space, and a liquid outletconduit extending radially outwardly from the vicinity of the centralarea of said suction space.
 2. The pulse generator of claim 1, saidcooperating surfaces being frustoconical.
 3. The pulse generator ofclaim 1, including a discharge passage in said head leading from saidcompression space, a valve closing said discharge passage, yieldablebiasing means urging said valve to a closed position, said valve beingarranged to be urged to an open position by pressure within saidcompression space.